North Korean leader Kim Jong Un, is shown reportedly taking part in the 5th Conference of the Workers' Party of Korea Cell Chairpersons in December 2017. (KCNA via KNS/AFP/Getty Images)

THERE HAS been a new flurry of discussion about military options the Trump administration may be considering for North Korea, including the “bloody nose” — a limited strike on a missile launch site or other select target meant to convey U.S. resolve and induce the regime of Kim Jong Un to back away from its reckless pursuit of a nuclear arsenal. Victor Cha, who had been selected by the White House to be ambassador to South Korea, saw his nomination derailed after he made the case against such military action in a meeting at the National Security Council. Last Wednesday he published an op-ed in The Post laying out his objections.

For now, it appears the White House is not arguing otherwise. With the Winter Olympics soon to begin in South Korea with the North’s participation, tensions are down somewhat; and administration officials say President Trump’s strategy of applying “maximum pressure” on Pyongyang through sanctions still has time to work. CIA Director Mike Pompeo recently said it would be “a handful of months” before North Korea could acquire the capacity to strike the United States homeland with a nuclear weapon.

Still, it’s more likely than not that the Kim regime eventually will return to its provocative tests and that the Trump administration will face the question of whether to take military action — large or small — to prevent it from reaching its goal. So it’s worth weighing the arguments of Mr. Cha, a veteran Asia expert who served in the George W. Bush administration and is considered a relative hawk on North Korea.

His analysis begins with a sobering conclusion: “North Korea, if not stopped, will build an arsenal with multiple nuclear missiles meant to threaten the U.S. homeland and blackmail us into abandoning our allies in Asia.” It could also sell the weapons to other states or to terrorists. That’s a threat that, as Mr. Trump has pointed out, previous presidents allowed to mature to a critical point — and that compels a robust response by his administration.

But is preemptive military action a conceivable option? Like other experts, Mr. Cha points to some crippling drawbacks. It would be virtually impossible to stop massive North Korean counterattacks, with artillery and perhaps chemical, biological or nuclear arms. While Mr. Trump may reckon that his first duty is to protect American cities from a North Korean strike, Mr. Cha points out that 230,000 Americans, the population of a medium-sized city, live in South Korea, and 90,000 are in Japan.

President Trump spoke with escapees from North Korea in the Oval Office on Feb. 2. (The Washington Post)

The argument for preemptive action is that the United States cannot suppose that it can deter the Kim regime from using its weapons, because it is irrational. It follows that allowing the dictator to acquire the capacity to strike the homeland is intolerable and the infliction of a “bloody nose” would convince him that the United States is serious about preventing it. But, Mr. Cha asks, “if we believe that Kim is undeterrable without such a strike, how can we also believe that a strike will deter him from responding in kind?” We can only hope that the president and his staff have done that same logical analysis — and that talk of a “bloody nose” is just that.